Plasma processing apparatus with heater and power frequency control

ABSTRACT

A plasma processing apparatus includes a chamber; a substrate support having a lower electrode, an electrostatic chuck, and a heater; a radio frequency power supply; a DC power supply; a first controller; and a second controller. The first controller controls the radio frequency power supply to supply a pulsed radio frequency power to the lower electrode periodically with a cycle defined by a first frequency, and controls the DC power supply to apply a pulsed negative voltage to the edge ring periodically with the cycle. The second controller includes a heater controller that controls the power by obtaining a resistance value of the heater from sample values of a current and a voltage supplied to the heater. The first frequency is different from a second frequency that is a sampling frequency of the sample value of the current and the sample value of the voltage in the second controller.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No.2019-115282, filed on Jun. 21, 2019, the entire contents of which areincorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a plasma processing apparatus andmethod.

BACKGROUND

A plasma processing apparatus is used for performing plasma processingon a substrate. The plasma processing apparatus includes a chamber, asubstrate support, and a radio frequency power supply. The substratesupport is disposed in the chamber. The substrate support includes alower electrode and an electrostatic chuck. The electrostatic chuck isdisposed on the lower electrode. An edge ring is disposed on thesubstrate support. The substrate is mounted on the electrostatic chuckand in a region surrounded by the edge ring. A radio frequency power issupplied from the radio frequency power supply to the lower electrode inorder to perform the plasma processing. A pulsed radio frequency powermay be periodically supplied from the radio frequency power supply tothe lower electrode.

When the plasma processing is performed, the edge ring is consumed and athickness of the edge ring is reduced. When the thickness of the edgering is reduced, a position of an upper end of a sheath above the edgering is lowered. Accordingly, ions are obliquely supplied from plasma toan edge of the substrate. In order to correct the position of the upperend of the sheath above the edge ring, a technique in which a negativevoltage is applied to the edge ring has been suggested. This techniqueis disclosed in Japanese Patent Application Publication No. 2019-4027.In the technique disclosed in Publication No. 2019-4027, a negativevoltage is applied to the edge ring during a period in which the pulsedradio frequency power is supplied to the lower electrode.

There is a demand for improving the accuracy of controlling atemperature of a heater disposed in the electrostatic chuck of theplasma processing apparatus.

SUMMARY

In accordance with an aspect of the present disclosure, there isprovided a plasma processing apparatus including: a chamber; a substratesupport disposed in the chamber and including a lower electrode, anelectrostatic chuck disposed on the lower electrode, and at least oneheater that is a resistance heating element disposed in theelectrostatic chuck; a radio frequency power supply electricallyconnected to the lower electrode; a DC power supply configured to applya negative voltage to an edge ring disposed on the substrate support; afirst controller configured to control the radio frequency power supplyand the DC power supply; and a second controller configured to control apower supplied from a heater power supply to the heater such that adifference between a current temperature and a set temperature of theheater is reduced. Further, the first controller controls the radiofrequency power supply to supply a pulsed radio frequency power to thelower electrode periodically with a cycle defined by a first frequency,and controls the DC power supply to apply a pulsed negative voltage tothe edge ring periodically with the cycle. The second controllerincludes a heater controller configured to control the power byobtaining a resistance value of the heater from a sample value of acurrent supplied to the heater and a sample value of a voltage appliedto the heater and determining the current temperature from theresistance value. The first frequency is different from a secondfrequency that is a sampling frequency of the sample value of thecurrent and the sample value of the voltage in the second controller.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and features of the present disclosure will become apparentfrom the following description of embodiments, given in conjunction withthe accompanying drawings, in which:

FIG. 1 schematically shows a plasma processing apparatus according to anembodiment;

FIG. 2 is a cross-sectional view of a substrate support of the plasmaprocessing apparatus according to the embodiment;

FIG. 3 shows a configuration related to a power supply to a heater and apower control for the heater in the plasma processing apparatusaccording to the embodiment;

FIG. 4 shows an example of a potential of a lower electrode and anexample of a voltage applied to a heater in the plasma processingapparatus shown in FIG. 1; and

FIG. 5 is a flowchart of a plasma processing method according to anembodiment.

DETAILED DESCRIPTION

Hereinafter, embodiments will be described in detail.

In one exemplary embodiment, a plasma processing apparatus is provided.The plasma processing apparatus includes a chamber, a substrate support,a radio frequency power supply, a DC power supply, a first controller,and a second controller. The substrate support includes a lowerelectrode, an electrostatic chuck, and a heater. The electrostatic chuckis disposed on the lower electrode. The heater that is a resistanceheating element disposed in the electrostatic chuck. The radio frequencypower supply is electrically connected to the lower electrode. The DCpower supply is configured to apply a negative voltage to an edge ring.The edge ring is disposed on the substrate support. The first controlleris configured to control the radio frequency power supply and the DCpower supply. The second controller is configured to control a powersupplied from a heater power supply to the heater such that a differencebetween a current temperature and a set temperature of the heater isreduced. The first controller controls the radio frequency power supplyto supply a pulsed radio frequency power to the lower electrodeperiodically with a cycle defined by a first frequency, and controls theDC power supply to apply a pulsed negative voltage to the edge ringperiodically with the cycle. The second controller is configured toobtain a resistance value of the heater from a sample value of a currentsupplied to the heater and a sample value of a voltage applied to theheater. The second controller is further configured to control the powerby determining the current temperature from the resistance value. Thefirst frequency is different from a second frequency that is a samplingfrequency of the sample value of the current and the sample value of thevoltage in the second controller.

The lower electrode and the heater in the electrostatic chuck arecapacitively coupled. Therefore, when the supply of the pulsed radiofrequency power and the application of the pulsed negative voltage arestarted, a noise current and a noise voltage are instantaneouslygenerated at the heater. In the above-described embodiment, the firstfrequency and the second frequency are different from each other, sothat the start timing of the supply of the pulsed radio frequency powerand the application of the pulsed negative voltage are only partiallysynchronized or not synchronized with the sampling timing of the currentand the voltage. Accordingly, the sample value of the current and thesample value of the voltage in which the influence of the noise issuppressed are obtained. In accordance with the above-describedembodiment, the resistance value is obtained from the sample value ofthe current and the sample value of the voltage, and the power iscontrolled based on the current temperature obtained from the resistancevalue. Accordingly, the accuracy of the heater temperature control isimproved.

In one exemplary embodiment, the first frequency is different from afactor of the second frequency, and the second frequency is differentfrom a factor of the first frequency. With such a configuration, thetiming of starting the supply of the pulsed radio-frequency power andthe application of the pulsed negative voltage and the timing ofsampling the current and the voltage are even less synchronized.

In one exemplary embodiment, the plasma processing apparatus furtherincludes, between the second controller and the heater, a capacitorconnected between a pair of lines that electrically connect the heaterand the heater power supply.

In one exemplary embodiment, the second controller further includes acurrent measuring device and a voltage measuring device. The currentmeasuring device is configured to measure the current supplied to theheater. The voltage measuring device is configured to measure thevoltage applied to the heater. The heater controller is configured toobtain the resistance value from the sample value of the currentmeasured by the current measuring device and the sample value of thevoltage measured by the voltage measuring device.

In one exemplary embodiment, the second controller further includes aswitching device. The switching device is connected between the heaterand the heater power supply. The heater controller is configured tocontrol the power by controlling a conducting state of the switchingdevice.

In one exemplary embodiment, the heater controller is configured todetermine the current temperature using an average value of sequentiallyobtained resistance values of the heater including the resistance value.

In another exemplary embodiment, a plasma processing method is provided.A plasma processing apparatus used to perform the plasma processingmethod includes a chamber, a substrate support, a radio frequency powersupply, a DC power supply, and a controller. The substrate supportincludes a lower electrode, an electrostatic chuck, and a heater. Theelectrostatic chuck is disposed on the lower electrode. The heater thatis a resistance heating element disposed in the electrostatic chuck. Theradio frequency power supply is electrically connected to the lowerelectrode. The DC power supply is configured to apply a negative voltageto an edge ring. The edge ring is disposed on the substrate support. Thecontroller is configured to a power supplied from a heater power supplyto the heater such that a difference between a current temperature and aset temperature of the heater is reduced. The plasma processing methodincludes generating plasma in the chamber. In the generating of plasma,a pulsed radio frequency power is supplied from the radio frequencypower supply to the lower electrode and a pulsed negative voltage isapplied from the DC power supply to the edge ring periodically with acycle defined by a first frequency in a state where a gas is suppliedinto the chamber. The plasma processing method further includescontrolling the power supplied to the heater by the controller duringexecution of the generating of plasma. The controller includes a heatercontroller. In the controlling of the power, the heater controllerobtains a resistance value of the heater from a sample value of acurrent supplied to the heater and a sample value of a voltage appliedto the heater. In the controlling of the power, the heater controllercontrols the power by determining the current temperature from theresistance value. The first frequency is different from a secondfrequency that is a sampling frequency of the sample value of thecurrent and the sample value of the voltage in the controller.

In one exemplary embodiment, the first frequency may be different from afactor of the second frequency, and the second frequency may bedifferent from a factor of the first frequency.

In one exemplary embodiment, between the controller and the heater, acapacitor may be connected between a pair of lines that electricallyconnect the heater and the heater power supply.

In one exemplary embodiment, in the controlling of the power, the heatercontroller may obtain the resistance value from the sample value of thecurrent measured by a current measuring device and the sample value ofthe voltage measured by a voltage measuring device.

In one exemplary embodiment, in the controlling of the power, the heatercontroller may control the power by controlling a conducting state of aswitching device connected between the heater and the heater powersupply.

In one exemplary embodiment, in the controlling of the power, the heatercontroller determines the current temperature using an average value ofsequentially obtained resistance values of the heater including theresistance value.

Hereinafter, various exemplary embodiments will be described in detailwith reference to the accompanying drawings. Like reference numeralswill be given to like or corresponding parts throughout the drawings.

FIG. 1 schematically shows a plasma processing apparatus according to anexemplary embodiment. A plasma processing apparatus 1 shown in FIG. 1 isa capacitively coupled plasma processing apparatus. The plasmaprocessing apparatus 1 includes a chamber 10. The chamber 10 has aninner space 10 s therein.

In the exemplary embodiment, the chamber 10 includes a chamber main body12. The chamber main body 12 has a substantially cylindrical shape. Theinner space 10 s is provided in the chamber main body 12. The chambermain body 12 is made of, e.g., aluminum. The chamber main body 12 iselectrically grounded. A plasma resistant film is formed on an innerwall surface of the chamber main body 12, i.e., a wall surface thatdefines the inner space 10 s. The plasma resistant film may be a filmformed by anodic oxidation treatment or a ceramic film such as a filmmade of yttrium oxide.

A passage 12 p is formed at a sidewall of the chamber main body 12. Asubstrate W is transferred between the inner space 10 s and the outsideof the chamber 10 through the passage 12 p. A gate valve 12 g isdisposed along the sidewall of the chamber main body 12 to open andclose the passage 12 p.

The plasma processing apparatus 1 further includes a substrate support16. The substrate support 16 is disposed in the chamber 10, i.e., in theinner space 10 s. The substrate support 16 is configured to support thesubstrate W supported thereon. The substrate W may have a disc shape.The substrate support 16 is supported by a supporting part 15. Thesupporting part 15 extends upward from a bottom portion of the chambermain body 12. The supporting part 15 has a substantially cylindricalshape. The supporting part 15 is made of an insulating material such asquartz.

The substrate support 16 includes a lower electrode 18 and anelectrostatic chuck 20. The substrate support 16 may further include anelectrode plate 21. The electrode plate 21 is made of a conductivematerial such as aluminum and has a substantially disc shape. The lowerelectrode 18 is disposed on the electrode plate 21. The lower electrode18 is made of a conductive material such as aluminum and has asubstantially disc shape. The lower electrode 18 is electricallyconnected to the electrode plate 21.

A flow path 18 f is formed in the lower electrode 18. The flow path 18 fis a channel for a heat exchange medium. As an example of the heatexchange medium, a liquid coolant or a coolant (e.g., Freon) for coolingthe lower electrode 18 by vaporization of the coolant is used. A supplydevice (e.g., a chiller unit) for supplying the heat exchange medium isconnected to the flow path 18 f. The supply device is disposed outsidethe chamber 10. The heat exchange medium is supplied from the supplydevice to the flow path 18 f through a line 23 a. The heat exchangemedium supplied to the flow path 18 f is returned to the supply devicethrough a line 23 b.

The electrostatic chuck 20 is disposed on the lower electrode 18. Whenthe substrate W is processed in the inner space 10 s, the substrate W ismounted on and held by the electrostatic chuck 20.

Hereinafter, FIG. 2 will be referred to together with FIG. 1. FIG. 2 isa cross-sectional view of the substrate support of the plasma processingapparatus according to the embodiment. The electrostatic chuck 20includes a main body 20 m and an electrode 20 e. The main body 20 m ismade of a dielectric material. The main body 20 m has a substantiallydisc shape. The electrode 20 e has a film shape and is disposed in themain body 20 m. A DC power supply 20 p is electrically connected to theelectrode 20 e through a switch 20 s. When a DC voltage is applied fromthe DC power supply 20 p to the electrode 20 e of the electrostaticchuck 20, an electrostatic attractive force is generated between theelectrostatic chuck 20 and the substrate W. Due to the generatedelectrostatic attractive force, the substrate W is attracted to and heldby the electrostatic chuck 20.

The edge ring ER is mounted on the substrate support 16. In theexemplary embodiment, the edge ring ER is mounted on an outer peripheralregion of the electrostatic chuck 20. The edge ring ER has a ring shape.The edge ring ER has conductivity. The edge ring ER is made of, e.g.,silicon or silicon carbide (SiC). The edge ring ER is electricallyconnected to the lower electrode 18 through a conductor 22. The edgering ER surrounds an edge of the substrate W. In other words, thesubstrate W is disposed on the electrostatic chuck 20 and in a regionsurrounded by the edge ring ER.

As shown in FIG. 1, the plasma processing apparatus 1 may furtherinclude a gas supply line 25. A heat transfer gas, e.g., He gas, issupplied from a gas supply unit through the gas supply line 25 to a gapbetween an upper surface of the electrostatic chuck 20 and a backside(bottom surface) of the substrate W.

The plasma processing apparatus 1 may further include a tubular member28 and an insulating member 29. The tubular member 28 extends upwardfrom the bottom portion of the chamber main body 12. The tubular member28 extends along an outer circumference of the supporting part 15. Thetubular member 28 is made of a conductive material and has asubstantially cylindrical shape. The tubular member 28 is electricallygrounded. The insulating member 29 is disposed on the tubular member 28.The insulating member 29 is made of an insulating material. Theinsulating member 29 is made of ceramic such as quartz. The insulatingmember 29 has a substantially cylindrical shape. The insulating member29 extends along outer circumferences of the electrode plate 21, thelower electrode 18, and the electrostatic chuck 20.

The plasma processing apparatus 1 further includes an upper electrode30. The upper electrode 30 is disposed above the substrate support 16.The upper electrode 30 blocks an upper opening of the chamber main body12 in cooperation with a member 32. The member 32 has an insulatingproperty. The upper electrode 30 is held at an upper portion of thechamber main body 12 through the member 32.

The upper electrode 30 includes a ceiling plate 34 and a holder 36. Abottom surface of the ceiling plate 34 defines the inner space 10 s. Theceiling plate 34 is provided with a plurality of gas injection holes 34a. The gas injection holes 34 a extend through the ceiling plate 34 in aplate thickness direction (vertical direction). The ceiling plate 34 ismade of, e.g., silicon, but is not limited thereto. Alternatively, theceiling plate 34 may have a structure in which a plasma resistant filmis formed on a surface of an aluminum base material. The plasmaresistant film may be a film formed by anodic oxidation treatment or aceramic film made of yttrium oxide.

The holder 36 detachably holds the ceiling plate 34. The holder 36 maymade of a conductive material such as aluminum. A gas diffusion space 36a is formed in the holder 36. A plurality of gas holes 36 b extendsdownward from the gas diffusion space 36 a. The gas holes 36 bcommunicate with the gas injection holes 34 a, respectively. A gas inletport 36 c is formed at the holder 36. The gas inlet port 36 c isconnected to the gas diffusion space 36 a. A gas supply line 38 isconnected to the gas inlet port 36 c.

A gas source group (GSG) 40 is connected to the gas supply line 38through a valve group (VG) 41, a flow rate controller group (FRCG) 42,and a valve group (VG) 43. The gas source group 40, the valve group 41,the flow rate controller group 42, and the valve group 43 constitute agas supply unit. The gas source group 40 includes a plurality of gassources. Each of the valve group 41 and the valve group 43 includes aplurality of valves (e.g., opening/closing valves). The flow ratecontroller group 42 includes a plurality of flow rate controllers. Eachof the flow rate controllers of the flow rate controller group 42 is amass flow controller or a pressure control type flow rate controller.The gas sources of the gas source group 40 are connected to the gassupply line 38 through the corresponding valves of the valve group 41,the corresponding flow rate controllers of the flow rate controllergroup 42, and the corresponding valves of the valve group 43. The plasmaprocessing apparatus 1 is configured to supply gases from one or moregas sources selected from among the plurality of gas sources of the gassource group 40 to the inner space 10 s at individually controlled flowrates.

A baffle plate 48 is disposed between the tubular member 28 and thesidewall of the chamber main body 12. The baffle plate 48 may be formedby coating ceramic such as yttrium oxide on an aluminum base material,for example. A plurality of through-holes is formed in the baffle plate48. Below the baffle plate 48, a gas exhaust line 52 is connected to thebottom portion of the chamber main body 12. A gas exhaust unit (GEU) 50is connected to the gas exhaust line 52. The gas exhaust unit 50includes a pressure controller such as an automatic pressure controlvalve, and a vacuum pump such as a turbo molecular pump to therebydecrease a pressure in the inner space 10 s.

In the exemplary embodiment, the plasma processing apparatus 1 mayfurther include a radio frequency power supply 61. The radio frequencypower supply 61 is configured to generate a radio frequency power HF forplasma generation. The radio frequency power HF has a frequency within arange of 27 MHz to 100 MHz, e.g., 40 MHz or 60 MHz. The radio frequencypower supply 61 is connected to the lower electrode 18 through amatching unit (MU) 63 and the electrode plate 21 to supply the radiofrequency power HF to the lower electrode 18. The matching unit 63 has amatching circuit configured to match an output impedance of the radiofrequency power supply 61 and an impedance of a load side (lowerelectrode 18 side). The radio frequency power supply 61 may not beelectrically connected to the lower electrode 18 and may be connected tothe upper electrode 30 through the matching unit 63.

The plasma processing apparatus 1 further includes a radio frequencypower supply 62. The radio frequency power supply 62 is configured togenerate a bias radio frequency power, i.e., a radio frequency power LF,for attracting ions to the substrate W. The frequency of the radiofrequency power LF is lower than the frequency of the radio frequencypower HF. The frequency of the radio frequency power LF is within arange of 400 kHz to 13.56 MHz, e.g., 400 kHz. The radio frequency powersupply 62 is connected to the lower electrode 18 through a matching unit(MU) 64 and the electrode plate 21 to supply the radio frequency powerLF to the lower electrode 18. The matching unit 64 has a matchingcircuit configured to match an output impedance of the radio frequencypower supply 62 and the impedance of the load side (the lower electrode18 side).

In this plasma processing apparatus 1, a gas is supplied to the innerspace 10 s. Then, one or both of the radio frequency power HF and theradio frequency power LF is supplied to excite the gas in the innerspace 10 s. Accordingly, plasma is generated in the inner space 10 s.The substrate W is processed by chemical species such as ions and/orradicals from the generated plasma.

The plasma processing apparatus 1 further includes a DC power supply 72.The DC power supply 72 is configured to apply a negative voltage to theedge ring ER through the lower electrode 18. By applying the negativevoltage from the DC power supply 72 to the edge ring ER, a thickness ofa sheath (plasma sheath) above the edge ring ER is adjusted.Accordingly, the incident direction of ions to the edge of the substrateW is adjusted.

The plasma processing apparatus 1 further includes a controller MC(first controller). The controller MC is a computer including aprocessor, a storage device, an input device, a display device, and thelike, and controls the respective components of the plasma processingapparatus 1. Specifically, the controller MC executes a control programstored in the storage device, and controls the respective components ofthe plasma processing apparatus 1 based on a recipe data stored in thestorage device. A process specified by the recipe data can be executedin the plasma processing apparatus 1 under the control of the controllerMC. Further, the plasma processing apparatus 1 can perform methodsaccording to various embodiments under the control of the controller MC.

Hereinafter, FIGS. 3 and 4 will be referred to together with FIGS. 1 and2. FIG. 3 shows a configuration related to a power supply to a heaterand a power control for the heater in the plasma processing apparatusaccording to the embodiment. FIG. 4 shows an example of a potential ofthe lower electrode and an example of a voltage applied to the heater inthe plasma processing apparatus shown in FIG. 1. In FIG. 4, thehorizontal axis indicates time. In FIG. 4, the potential of the lowerelectrode indicates a potential of a power supply line FL shown in FIG.2. The power supply line FL is connected to the lower electrode 18through the electrode plate 21. The radio frequency power supply 61 isconnected to the power supply line FL through the matching unit 63. Theradio frequency power supply 62 is connected to the power supply line FLthrough the matching unit 64. Further, the DC power supply 72 isconnected to the power supply line FL.

In the plasma processing apparatus 1, in order to generate plasma, thecontroller MC controls the radio frequency power supply 62 and/or theradio frequency power supply 61 to supply the pulsed radio frequencypower LF and/or the pulsed radio frequency power HF to the lowerelectrode 18 at every cycle PT. The cycle PT is defined by a firstfrequency f1. In other words, the cycle PT is a reciprocal of the firstfrequency f1. The radio frequency power LF and/or the radio frequencypower HF is supplied to the lower electrode 18 during a first period ofthe cycle PT. The radio frequency power is not supplied to the lowerelectrode 18 during a remaining second period of the cycle PT.Alternatively, the level of the radio frequency power supplied in thefirst period may be reduced in the second period.

Further, the controller MC controls the DC power supply 72 to apply thepulsed negative voltage to the edge ring ER at every cycle PT. In otherwords, the controller MC controls the DC power supply 72 to apply thepulsed negative voltage to the edge ring ER in synchronization with thesupply of the pulsed radio frequency power LF and/or the pulsed radiofrequency power HF. In the first period of the cycle PT, the DC powersupply 72 applies a negative voltage to the edge ring ER. In theremaining second period of the cycle PT, the application of the negativevoltage from the DC power supply 72 to the edge ring ER is stopped.Alternatively, the absolute value of the voltage applied from the DCpower supply 72 to the edge ring ER in the second period may be smallerthan the absolute value of the voltage applied from the DC power supply72 to the edge ring ER in the first period.

The control of the radio frequency power supply 62 and/or the radiofrequency power supply 61 and the DC power supply 72 by the controllerMC causes temporal changes in the potential of the lower electrode 18 asshown in FIG. 4.

As shown in FIGS. 2 and 3, the substrate support 16 further includes oneor more heaters 19. In the exemplary embodiment, the substrate support16 has a plurality of heaters 19. Each of the heaters 19 is a resistanceheating element. The heaters 19 are disposed in the electrostatic chuck20.

Power is supplied from a heater power supply 74 to the heaters 19. Theheaters 19 are connected to one or more first lines L1, and arerespectively and electrically connected to the heater power supply 74through the first lines L1. Further, the heaters 19 are electricallyconnected to the heater power supply 74 through a second line L2. Thesecond line L2 is a common line. In other words, the heaters 19 areelectrically connected to the heater power supply 74 through a pair oflines including one corresponding first line L1 and the second line L2.

In the exemplary embodiment, a filter group FTG1 may be disposed betweenthe heaters 19 and the heater power supply 74. The filter group FTG1includes one or more filters FT11 and a filter FT12. Each of the filtersFT11 and the filter FT12 are an LC filter that blocks or attenuates aradio frequency power from a corresponding heater 19 to the heater powersupply 74. An inductor of each of the filters FT11 constitutes a part ofa corresponding first line L1. A capacitor of each of the filters FT11is connected between the corresponding first line L1 and the ground. Theinductor of the filter FT12 constitutes a part of the second line L2.The capacitor of the filter FT12 is connected between the second line L2and the ground.

In the exemplary embodiment, a filter group FTG2 may be disposed betweenthe heaters 19 and the heater power supply 74 and further may bedisposed between the filter group FTG1 and the heater power supply 74.The filter group FTG2 includes one or more filters FT21 and a filterFT22. Each of the filters FT21 and the filter FT22 are an LC filter thatblocks or reduces EMC noise from the corresponding heater 19 to theheater power supply 74. An inductor of each of the filters FT21constitutes a part of the corresponding first line L1. A capacitor ofeach of the filters FT21 is connected between the corresponding firstline L1 and the ground. The inductor of the filter FT22 constitutes apart of the second line L2. The capacitor of the filter FT22 isconnected between the second line L2 and the ground.

In the exemplary embodiment, a capacitor 76 is connected between each ofthe first lines L1 and the second line L2. In other words, the capacitor76 is connected between a pair of lines that electrically connect acorresponding heater 19 and the heater power supply 74. One end of thecapacitor 76 may be connected to the corresponding first line L1 betweenthe inductor of the corresponding filter FT11 and the inductor of thecorresponding filter FT21. The other end of the capacitor may beconnected to the second line L2 between the inductor of the filter FT12and the inductor of the filter FT22.

The plasma processing apparatus 1 further includes a controller 80(second controller). The controller 80 controls the power supplied fromthe heater power supply 74 to each of the heaters 19 such that thedifference between the current temperature and the set temperature ofthe corresponding heater 19 is reduced. Hereinafter, the control of thepower supplied to one heater 19 by the controller 80 will be described.The control of the power supplied to the other heaters 19 by thecontroller 80 is performed in the same manner.

The controller 80 has a heater controller (HC) 82. The heater controller82 includes, e.g., a processor. The heater controller 82 obtains aresistance value of the heater 19 from a sample value of a currentsupplied to the heater 19 and a sample value of a voltage applied to theheater 19. A sampling frequency of the sample value of the currentsupplied to the heater 19 and the sample value of the voltage applied tothe heater 19 is the second frequency f2. The heater controller 82determines a current temperature of the heater 19 from the obtainedresistance value. The heater controller 82 may determine the currenttemperature of the heater 19 from the resistance value that is obtainedby referring to a table that defines, e.g., the relationship between theresistance value and the temperature. In the exemplary embodiment, theheater controller 82 may be configured to determine the currenttemperature using an average value of sequentially obtained resistancevalues of the heater 19. The heater controller 82 controls the amount ofpower supplied to the heater 19 such that the difference between thedetermined current temperature and the set temperature is reduced. Thecontrol of the power by the heater controller 82 may be theproportional-integral-derivative (PID) control.

In the exemplary embodiment, the controller 80 may further include oneor more switching devices 83. Each of the switching devices 83 isconnected between a corresponding one of the heaters 19 and the heaterpower supply 74. When each of the switching devices 83 is in aconducting state, the power is supplied from the heater power supply 74to the corresponding heaters 19. When each of the switching devices 83is in a non-conducting state, the power supply from the heater powersupply 74 to the corresponding heaters 19 is stopped. The heatercontroller 82 can control the power supplied to the heaters 19 bycontrolling the conducting states of the corresponding switching devices83.

In the exemplary embodiment, the controller 80 may further include oneor more current measuring devices (CMD) 84 and a voltage measuringdevice (VMD) 86. The current measuring devices 84 are configured torespectively measure the currents supplied to the heaters 19 from theheater power supply 74. The voltage measuring device 86 is configured tomeasure the voltage applied to the heaters 19. The heater controller(HC) 82 obtains the resistance values of the heaters 19 from the samplevalues of the currents respectively measured by the correspondingcurrent measuring devices 84 and the sample value of the voltagemeasured by the voltage measuring device 86.

In the exemplary embodiment, the heater power supply 74 is connected toa single line ML. The single line ML is connected to one or more linesL11. The lines L11 are connected to the corresponding switching devices83. The current measuring devices 84 are configured to measure thecurrents flowing through the corresponding lines L11. The voltagemeasuring device 86 is configured to measure the voltage between theline ML and the second line L2.

The above-described second frequency f2 is different from the firstfrequency f1. In the exemplary embodiment, the first frequency f1 isdifferent from a factor of the second frequency f2, and the secondfrequency f2 is different from a factor of the first frequency f1. Oneof the first frequency f1 and the second frequency f2 may be a naturalnumber, and the other frequency may not be a natural number. In oneexample, the second frequency f2 is 2 kHz, and the first frequency f1 is2.1 kHz.

In the plasma processing apparatus 1, the lower electrode 18 and theheaters 19 in the electrostatic chuck 20 are capacitively coupled.Therefore, when the supply of the pulsed radio frequency power (LFand/or HF) and the application of the pulsed negative voltage arestarted, a noise current and a noise voltage are instantaneouslygenerated at each of the heaters 19 (see FIG. 4 showing the applicationof the voltage to the heaters). In the plasma processing apparatus 1,the first frequency f1 and the second frequency f2 are different fromeach other. Thus, in the plasma processing apparatus 1, the start timingof the supply of the pulsed radio frequency power (LF and/or HF) and theapplication of the pulsed negative voltage are only partiallysynchronized or not synchronized with the sampling timing of the currentand the voltage. Accordingly, the heater controller 82 obtains thesample values of the current and the voltage in which the influence ofnoise is suppressed. In accordance with the plasma processing apparatus1, the resistance values are obtained from the sample values of thecurrents and the voltages obtained in the above manner, and the power iscontrolled based on the current temperatures obtained from suchresistance values, which makes it possible to control the temperaturesof the respective heaters 19 with high accuracy.

In the exemplary embodiment, as described above, the first frequency f1is different from a factor of the second frequency f2, and the secondfrequency f2 is different from a factor of the first frequency f1. Inaccordance with the present embodiment, the timing of starting thesupply of the pulsed radio-frequency power and the application of thepulsed negative voltage and the timing of sampling the current and thevoltage are even less synchronized.

FIG. 5 shows a flowchart of a plasma processing method according to anexemplary embodiment. In the following description, the case ofperforming the plasma processing method shown in FIG. 5 (hereinafterreferred to as “method MT”) using the plasma processing apparatus 1 willbe described as an example.

In the method MT, step ST1 is executed. In step ST1, plasma is generatedin the chamber 10. In step ST1, while a gas is supplied to the chamber10, the pulsed radio frequency power LF and/or the pulsed radiofrequency power HF is supplied from the radio frequency power supply 62and/or the radio frequency power supply 61 to the lower electrode 18 atevery cycle PT. Further, in step ST1, a pulsed negative voltage isapplied from the DC power supply 72 to the edge ring ER at every cyclePT. The supply of the pulsed radio frequency power LF and/or the pulsedradio frequency power HF and the application of the pulsed negativevoltage to the edge ring ER are synchronized. The cycle PT is defined bythe first frequency f1 as described above.

In order to execute step ST1, the controller MC controls the gas supplyunit of the plasma processing apparatus 1 to supply the gas into thechamber 10. In order to execute step ST1, the controller MC controls thegas exhaust unit 50 to set the pressure in the chamber 10 to a desiredpressure. In order to execute step ST1, the controller MC controls theradio frequency power supply 62 and/or the radio frequency power supply61 to supply the pulsed radio frequency power LF and/or the pulsed radiofrequency power HF. Further, in order to execute step ST1, thecontroller MC controls the DC power supply 72 to apply the pulsednegative voltage to the edge ring ER.

Step ST2 is executed during the execution of step ST1. In step ST2, thepower supplied from the heater power supply 74 to each of the heaters 19is controlled by the controller 80. Specifically, as described above,the heater controller 82 of the controller 80 obtains the resistancevalues of the heaters 19 from the sample values of the currents suppliedto the heaters 19 and the sample values of the voltages applied to theheaters 19. As described above, the second frequency f2, which is thesampling frequency of the sample value of the current supplied to eachof the heaters 19 and the sample value of the voltage applied to thecorresponding heater 19, is different from the first frequency f1.

In step ST2, the heater controller 82 determines current temperatures ofthe heaters 19 from the obtained resistance values, respectively. Thecurrent temperatures of the heaters 19 may be determined using anaverage value of sequentially obtained resistance values, as describedabove. In step ST2, the heater controller 82 controls the power suppliedfrom the heater power supply 74 to the heaters 19 such that theindividual differences between the determined current temperatures andthe set temperatures are reduced.

While various embodiments have been described above, various omissions,substitutions, and changes may be made without being limited to theabove-described embodiments. Further, other embodiments can beimplemented by combining elements in different embodiments.

For example, in another embodiment, the plasma processing apparatus maybe any type of a plasma processing apparatus different from thecapacitively coupled plasma processing apparatus. For example, aninductively coupled plasma processing apparatus, a plasma processingapparatus for generating plasma using surface waves such as microwaves,or the like, may be used as the plasma processing apparatus.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the disclosures. Indeed, the embodiments described herein maybe embodied in a variety of other forms. Furthermore, various omissions,substitutions and changes in the form of the embodiments describedherein may be made departing from the spirit of the disclosures. Theaccompanying claims and their equivalents are intended to cover suchforms or modifications as would fall within the scope and spirit of thedisclosures.

The invention claimed is:
 1. A plasma processing apparatus comprising: achamber; a substrate support disposed in the chamber and including alower electrode, an electrostatic chuck disposed on the lower electrode,and at least one heater that is a resistance heating element disposed inthe electrostatic chuck; a radio frequency power supply electricallyconnected to the lower electrode; a DC power supply configured to applya negative voltage to an edge ring disposed on the substrate support; afirst controller configured to control the radio frequency power supplyand the DC power supply; and a second controller configured to control apower supplied from a heater power supply to the heater such that adifference between a current temperature and a set temperature of theheater is reduced, wherein the first controller controls the radiofrequency power supply to supply a pulsed radio frequency power to thelower electrode periodically with a cycle defined by a first frequency,and controls the DC power supply to apply a pulsed negative voltage tothe edge ring periodically with the cycle, the second controllerincludes a heater controller configured to control the power byobtaining a resistance value of the heater from a sample value of acurrent supplied to the heater and a sample value of a voltage appliedto the heater and determining the current temperature from theresistance value, and the first frequency is different from a secondfrequency that is a sampling frequency of the sample value of thecurrent and the sample value of the voltage in the second controller. 2.The plasma processing apparatus of claim 1, wherein the first frequencyis different from a factor of the second frequency, and the secondfrequency is different from a factor of the first frequency.
 3. Theplasma processing apparatus of claim 1, further comprising, between thesecond controller and the heater, a capacitor connected between a pairof lines that electrically connect the heater and the heater powersupply.
 4. The plasma processing apparatus of claim 2, furthercomprising, between the second controller and the heater, a capacitorconnected between a pair of lines that electrically connect the heaterand the heater power supply.
 5. The plasma processing apparatus of claim1, wherein the second controller further includes: a current measuringdevice configured to measure the current supplied to the heater and avoltage measuring device configured to measure the voltage applied tothe heater, wherein the heater controller is configured to obtain theresistance value from the sample value of the current measured by thecurrent measuring device and the sample value of the voltage measured bythe voltage measuring device.
 6. The plasma processing apparatus ofclaim 2, wherein the second controller further includes: a currentmeasuring device configured to measure the current supplied to theheater and a voltage measuring device configured to measure the voltageapplied to the heater, wherein the heater controller is configured toobtain the resistance value from the sample value of the currentmeasured by the current measuring device and the sample value of thevoltage measured by the voltage measuring device.
 7. The plasmaprocessing apparatus of claim 1, wherein the second controller furtherincludes: a switching device connected between the heater and the heaterpower supply, wherein the heater controller is configured to control thepower by controlling a conducting state of the switching device.
 8. Theplasma processing apparatus of claim 2, wherein the second controllerfurther includes: a switching device connected between the heater andthe heater power supply, wherein the heater controller is configured tocontrol the power by controlling a conducting state of the switchingdevice.
 9. The plasma processing apparatus of claim 1, wherein theheater controller is configured to determine the current temperatureusing an average value of sequentially obtained resistance values of theheater including the resistance value.
 10. The plasma processingapparatus of claim 2, wherein the heater controller is configured todetermine the current temperature using an average value of sequentiallyobtained resistance values of the heater including the resistance value.